An airplane is propelled by one or several propulsive assemblies comprising a turbojet engine housed in a tubular nacelle. Each propulsive assembly is attached to the airplane by a strut generally situated under a wing or at the fuselage.
A nacelle generally has a structure comprising an air inlet upstream from the engine, a middle section intended to surround a fan of the turbojet engine, and a downstream section designed to surround the combustion chamber of the turbojet engine and housing thrust reverse means.
The air inlet comprises, on one hand, an intake lip adapted to allow optimal collection toward the turbojet engine of the air necessary to supply the fan and the internal compressors of the turbojet engine, and on the other hand, a downstream structure on which the lip is attached and designed to suitably channel the air toward the blades of the fan, said downstream structure comprising an outer shroud and an inner acoustic panel. The assembly is attached upstream from a case of the fan belonging to the middle section of the nacelle.
The middle structure surrounds the fan and generally breaks down into an inner wall forming said fan case and an outer wall assuming the form of removable cowls mounted pivotably around a longitudinal axle forming a hinge in the upper portion (at 12:00) of the nacelle in order to allow access to the inside of the nacelle.
The assembly of these various elements (mobile cowls, case, air intake lip, outer shroud, acoustic panel) creates many aerodynamic breaks due to the presence of offsets and gaps between these elements inherent to their fastening together. Moreover, the mobile cowls are mounted on hinges, also generating aerodynamic disturbances.
One solution to improve the aerodynamic continuity of the outer surface of a nacelle was the object of French patent applications no. 06/08599 and no. 07/01256, not yet published.
This solution consists of integrating the air intake lip into the outer shroud, including all or part of the cowl there surrounding the fan case so as to form a single-piece structure. The whole of the wall thus formed is mounted mobile in translation.
The French patent application, not yet published, registered under number 07/03699 describes a manual locking system of said air intake structure and an associated manual system for helping the translation.
In a turbojet engine nacelle having such a translatable structure, the inner edge of the air intake lip comes, when said translatable structure is in closed position, into contact with a zone upstream from an inner wall of the air intake structure, inner wall generally realized in the form of an acoustic panel.
The translatable structure is guided and maintained on a fixed structure, comprising the inner wall of the air intake structure, by a plurality of rails.
The interface is made sealed by a joint system and is reinforced by a system of centering pins arranged on the periphery of the air intake lip/acoustic shroud junction and making it possible to improve its resistance to radial movements.
The maintenance of the mobile structure along longitudinal directions is done primarily by bolting the mobile structure on a fixed structure in a zone close to an installation interface of the acoustic shroud on the fan case.
Such a locking system therefore requires a large number of fixing means, the assembly and disassembly of which are long and tedious.
Also known is a manual locking system comprising a system for gripping the mobile structure by the handle at the end of maneuver of the structure. This technique makes it possible to avoid a long and tedious assembly/disassembly with a system of maintenance by bolting. However, such a system is not suited to motorized driving of the mobile structure since the manual drive system and the locking are coupled. One will also note that the adjustment of the gripping of the bolts is also long and tedious.
Because of these, there is a need for a locking system of such a mobile structure making it possible to resolve all or part of these problems.